U.S. Pat. No. 3,775,942, issued to Powell et al and assigned to the present assignee, discloses freeze drying apparatus wherein shelves therein may be adjustably spaced on pegboard support members by means of holes provided therein at predetermined locations, and to additional means for stoppering the vials.
U.S. Pat. No. 3,448,556, discloses freeze drying apparatus wherein partially stoppered vials containing the product are fully stoppered on shelves disposed between an uppermost shelf which moves downwardly and a lowermost shelf which is caused to move upwardly.
Other patents disclose diverse mechanisms useful in lyophilization, including means for adjusting the space between adjacent shelves to accommodate containers of varying sizes, vacuum capping of containers, automatic vial stoppering, shelf adjustment and movement, and the like. As far as known, none teach or suggest freeze drying apparatus having a tall vacuum drying chamber wherein upper shelves therein are depressable to eye level height in order to facilitate manual loading thereon of partially stoppered containers with product therein, typically pharmaceutical or biological liquids, while sequentially elevating the loaded shelves to their initial position. Lower shelves, of course, will be individually manually loaded, as accomplished heretofore.
Current trends in the pharmaceutical freeze drying industry lean toward the utilization of larger and taller vacuum drying chambers in order to accommodate larger batch sizes of product with accompanying cost savings. The design of these larger chambers, however, requires the upper shelves to be positioned considerably above the head of an operator of average height, rendering manual loading and unloading of the upper shelves difficult.
The present invention provides apparatus which permits an intermediately positioned shelf to function as a supporting shelf for the stacking thereon of the upper shelves. That is, the shelf immediately above the supporting shelf is depressed to rest upon the supporting shelf. Simultaneously therewith, each of the remaining upper shelves is similarly moving downwardly resulting in a sequential stacking of the upper shelves on the supporting shelf, the uppermost shelf within the chamber forming the uppermost shelf of the stack. The stacked uppermost shelf, now lowered to about eye level height, is manually loaded before being elevated a few inches to a predetermined position to thus expose the next shelf therebelow for manual loading, and so on. After each of the upper shelves has been returned to its original position, the supporting shelf is manually loaded. Shelves below the supporting shelf may already have been manually loaded as in the past.
It is thus apparent that an operator of average height may readily manually load a large vacuum drying chamber wherein the uppermost shelf to be loaded, while in its initial or original position within the chamber, may be almost 8 feet above the floor, as in the apparatus to be described hereinafter.
After the product is freeze dried, the operator activates stoppering means which continuously elevates all shelves toward a stationary uppermost shelf (which is not loaded) for complete stoppering of the partially stoppered vials on each of the shelves in sequential ascending order. The stoppering means of the present apparatus is similar to that disclosed in the aforementioned patent to Powell et al assigned to the present assignee .